1. Field of the Invention
One or more embodiments of the present invention relate to thrombospondin 1 (TSP-1), TSP-2, interleukin 17B receptor (IL-17BR), and heparin-binding epidermal growth factor-like growth factor (HB-EGF) associated with stem cell activity, for example, activity of a mesenchymal stem cell (MSC), and use thereof.
2. Description of the Related Art
Cartilage is a kind of dense and thick connective tissue, and is composed of chondrocytes distributed in a stiff yet flexible gel-like matrix. Cartilage does not contain blood vessels, and the chondrocytes are supplied by diffusion via the matrix. Cartilage is classified into three types: hyaline cartilage (for example, cartilage of the nose, organs and bronchiole and articular cartilage), elastic cartilage (for example, cartilage of the external ear, part of the Eustachian tube, and part of laryngeal cartilage), and fibrocartilage (for example, meniscus and endplate cartilage). The main purpose of cartilage is to provide a framework upon which bone deposition can begin and provide a smooth surface allowing free joint movement between bones. In addition, the cartilage provides a strong yet flexible support.
There are various therapies for treating a cartilage injury or cartilage failure. Osteoarthritis is degenerative arthritis that is, in general, relatively mild at first, but aggravates with time and wear. In terms of medical treatment, medicines such as an anti-inflammatory agent (for example, diclofenac, ibuprofen, or naproxen), a COX-2 selective inhibitor, hydrocortisone, glucosamine, and chondroitin sulfate are known to relieve pain due to cartilage loss.
Thrombospondin-2 (TSP-2) is a secretory, extracellular matrix glycoprotein that exhibits strong anti-angiogenic activity (Bornstein et al., 2000, Matrix Biology 19: 557-568).
Thrombospondin-1 (TSP-1) is a multimeric glycoprotein composed of identical monomers. The monomer has a molecular weight of about 185 KDa in sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) under reducing conditions. The predominant multimer is a trimer having a molecular weight of about 450 KDa on non-reducing gels, and the molecular weights by sedimentation equilibrium are similar, at 135 kDa for monomers and 420 kDa for trimers. The predicted molecular weight from a sequence of amino acid residues in the monomer is 127,524 Da, which does not include contributions from glycosylation and β-hydroxylation. TSP-1 is known to be involved in cell adhesion, proliferation, and chemotaxis. It has also been reported that TSP-1 may be involved in the progression of malignant tumors.
Interleukin-17B receptor (IL-17BR) is a protein in humans that is encoded by the IL17BR gene. IL-17BR is a cytokine receptor that specifically binds to IL17B and IL17E, but does not bind to IL17 and IL170.
Heparin-binding epidermal growth factor-like growth factor (HB-EGF) exerts its biological activities by binding to an erb class of EGF receptors (EGFR). HB-EGF binds heparin with high affinity. HB-EGF binds to EGFR to modulate the biological effects of the growth factor on target cells, including cellular migration and proliferation. HB-EGF is mitogenic for fibroblasts, smooth muscle cells, and epithelial cells. HB-EGF is a heat-sensitive, cationic protein, with a molecular weight of approximately 22,000 Da. HB-EGF is known to treat symptoms associated with intestinal ischemia, for example, intestinal cell necrosis and enterocolitis. In addition, HB-EGF is known to inhibit liver diseases and liver cell death and facilitate liver reproduction in mammals.
In spite of these disclosures, association of chondrogenic differentiation of stem cells with TSP-1, TSP-2, IL-17BR, and HB-EGF has still not been proven.